A Hydra is a small freshwater, tentacled animal, whose mouth actually disappears every time it closes. According to a a scientist quoted in Ed Yongs blog on National Geographic,  “when a hydra closes its mouth, it obliterates it.” This means to open it again, it has to tear itself apart.

We all know about the Hydra from Greek mythology, big venomous monster with the annoying ability to regrow its heads. Well this little guy has a lot of similarities according to Ed Yongs blog. Although not big and scary, their ability to regenerate even has some scientists suggesting they are effectively immortal. Have a watch…

Why did they develop this way? No one seems to know…